We expected the PlayStation 3 to ship with several games that first appeared on the Xbox 360, similar to how the Xbox 360 had a lot of Xbox ports at launch. And the PS3 did indeed arrive with a good number of games that originally shipped for the Xbox 360. This gave us the perfect opportunity to compare the graphics on both systems with several cross-platform games. You'd think that the PS3 versions would be exactly the same or slightly superior to the Xbox 360 versions, since many of these games appeared on the 360 months ago, but it seems like developers didn't use the extra time to polish up the graphics for the PS3. We found that the Xbox 360 actually had better graphics in the majority of the games we compared.
This is a very interesting comparison of graphics between these two consoles in a variety of games. The results may surprise you.